Ferrari set the pace as Gasly suffers 'pretty big crash' in F1 testing
Ferrari once again impressed during Formula One testing but Pierre Gasly's work on Thursday was cut short by a heavy crash in his Red Bull.
Charles Leclerc posted a best lap time of one minute and 16.231 seconds, comfortably the quickest during the pre-season sessions so far, during the morning session in Barcelona.
To put the 21-year-old's effort into context, it was just 0.058secs slower than the lap Lewis Hamilton produced to claim pole position for the 2018 Spanish Grand Prix.
While Leclerc saw his afternoon end early, his Ferrari SF90 stopped on the track and had to be removed on a flat-bed truck, he warned the rest of the grid that there is still more to come from the car.
"Obviously I think as every team we are not flat out," he said after the morning session.
"There's still some margin, a bit obviously in myself. I still have to learn, I get more comfortable with the car lap after lap and with the car itself, so it's looking good for now."
Gasly, meanwhile, went into a spin at Turn 9, sending him off the track and into the barriers.
It was the second incident during testing for the Frenchman - he also crashed on his first day of running last week - since joining Red Bull from Toro Rosso.
"I made a mistake in Turn 9 and basically lost the car. It was a pretty big crash, one of the biggest crashes I have had so far," Gasly - who posted the day's fourth fastest time prior to his accident - told reporters.
"It will be a long night for the mechanics, I'm sorry for them. But what is important is that Max [Verstappen] is back in the car and we focus on the positives."
Toro Rosso's Alexander Albon ended the day second on the timesheets behind Leclerc, with Lando Norris in third position in his McLaren.
As for Mercedes, Hamilton managed 83 laps while team-mate Valtteri Bottas completed 96. They finished in 10th and 13th place respectively.
Friday is the final day of testing ahead of the season-opening Grand Prix in Australia on March 17.